JP2016087567A - Membrane module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove a floating pollutant adhered to an outer peripheral part of a membrane member with a good efficiency in a membrane module which is used for a liquid treatment of removing impurities in a liquid and so on.SOLUTION: A membrane module 1 is equipped with: a housing 2; a membrane member 3 provided in the housing 2; and an air diffusion member 4 which is provided below the membrane member 3 in the housing 2 and has plural vent holes 43 for supplying a gas to the membrane member 3. A dimension of the air diffusion member 4 in a horizontal direction is larger than a dimension of the membrane member 3 in a horizontal direction. A part of the plural vent holes 43 is so provided as to be positioned on a horizontal direction outer side with respect to the membrane member 3.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a membrane module used for liquid treatment for removing impurities in a liquid.

  Conventionally, a membrane module having a hollow fiber membrane has been used in water treatment for removing impurities in water. In the filtration process of water treatment, raw water (water before filtration) is supplied into the membrane module through the raw water inlet provided in the membrane module, and the filtered water that has passed through the membrane passes through the filtered water outlet provided in the membrane module. Discharged outside.

  In the membrane module, when a water treatment filtration step is performed, substances removed from the water (suspended solids (SS)) accumulate on the surface of the membrane. Thus, it is one of the important issues to efficiently remove the suspended contaminants deposited on the surface of the film.

  In general, removal of suspended contaminants is performed by so-called backwashing (backwashing). In the backwashing process, a fluid flow in the opposite direction to the filtration process is formed in the membrane module in order to float the suspended contaminants deposited and adhered to the surface of the membrane from the membrane. That is, fluid (gas or liquid) is supplied into the membrane module through the filtered water outlet, and the fluid that has passed through the membrane is discharged out of the membrane module through the raw water inlet.

  The suspended pollutant that has been partially floated from the surface of the film by the backwashing process is peeled off from the surface of the film by the subsequent bubbling process. In this bubbling process, air is supplied in a state where the membrane module is filled with water, and the membrane is shaken by the bubble of the supplied air. As a result, suspended contaminants on the surface of the membrane are peeled off. The membrane module includes a diffuser member having a plurality of air holes for supplying air to the hollow fiber membrane in the bubbling step (Patent Documents 1 to 4).

  In the hollow fiber membrane module of Patent Document 1, an air disperser for dispersing and guiding the air supplied from the air supply header is provided on the lower side of the hollow fiber membrane. The hollow fiber membrane module of Patent Document 2 has an air supply unit provided on a resin plate. In Patent Document 2, when the cross-sectional area of the air supply unit is S, a through hole is provided only in a region corresponding to 0.5S in the center of the air supply unit. In the hollow fiber membrane module of Patent Document 3, an air diffusion mechanism that generates bubbles from the lower end side of the hollow fiber membrane is formed so that air can be diffused into the hollow fiber membrane extending in the vertical direction. In the immersion membrane separator of Patent Document 4, an air diffuser having gas introduction holes is provided.

Japanese Patent Laid-Open No. 11-033367 JP 2006-239642 A JP 2009-285532 A Japanese Patent No. 4430244

  However, in any of the air supply structures disclosed in any of Patent Documents 1 to 4, there is a problem that the suspended contaminants attached to the outer peripheral portion of the hollow fiber membrane cannot be efficiently removed.

  An object of the present invention is to efficiently remove suspended contaminants attached to the outer peripheral portion of a membrane member in a membrane module used for liquid treatment for removing impurities in a liquid.

  The membrane module of the present invention includes a housing, a membrane member provided in the housing, and a plurality of vent holes provided below the membrane member in the housing for supplying gas to the membrane member And an air diffuser member. The dimension of the air diffusing member in the horizontal direction is larger than the dimension of the membrane member in the horizontal direction. A part of the plurality of vent holes is provided so as to be located on the outer side in the horizontal direction with respect to the membrane member.

  In the present invention, since a part of the plurality of vent holes in the diffuser member is provided so as to be located outside in the horizontal direction with respect to the membrane member, in the bubbling process, the gas supplied into the housing A part of the membrane member is guided to the upper side of the air diffusing member by a vent hole located on the outer side in the horizontal direction from the membrane member, and reaches the outer peripheral portion of the membrane member by rising in the liquid. As described above, in the present invention, since a part of the gas supplied into the membrane module can be reliably supplied to the outer peripheral portion of the membrane member, the floating contaminants adhering to the outer peripheral portion of the membrane member are removed from the membrane member. Can be efficiently peeled off and removed from the surface.

  In the membrane module, it is preferable that a gap is formed between the housing and the air diffusing member.

  In this configuration, for example, a gap is formed between the housing and the air diffuser by adopting a structure in which the inner dimension of the housing in the horizontal direction is larger than the dimension of the air diffuser in the horizontal direction. This gap can function as a passage for guiding the suspended pollutant material that has been peeled off from the surface of the membrane due to the bubbling process to a position below the diffuser member. Thereby, the floating pollutant removed from the surface of the membrane can be efficiently discharged out of the housing.

  In the membrane module, it is preferable that an inner diameter of the outermost vent hole among the plurality of vent holes is larger than an inner diameter of the vent hole provided on the inner side.

  In this configuration, the vent hole located on the outermost side in the horizontal direction is provided so as to be located on the outer side in the horizontal direction with respect to the membrane member. In this configuration, the inner diameter of the vent hole located on the outermost side in the horizontal direction is made larger than the inner diameter of the vent hole provided on the inner side in the horizontal direction. Therefore, in this configuration, compared to the case where the inner diameters of the plurality of vent holes are the same, the ratio of the gas guided to the upper side of the air diffuser through the outermost vent holes passes through the inner vent holes. It can be increased compared with the ratio of gas to be used. Thereby, in this structure, compared with the case where the internal diameter of several ventilation holes is the same, the floating pollutant adhering to the outer peripheral part of a film | membrane member can be removed still more efficiently.

  In the membrane module, the diffuser member is provided below the plate-like main body portion provided with the plurality of air holes and the main body portion, and temporarily accommodates the gas supplied into the housing. A plurality of vent holes provided in the main body portion on the outer side in the horizontal direction than the gas receiving portion, and the gas receiving portion is accommodated in the gas receiving portion. It is preferable to have a plurality of dispersion holes for dispersing the gas to the outside in the horizontal direction below the gas receiving part below the main body part.

  In this configuration, a gas receiving portion is provided below the main body portion of the air diffusion member, and the gas temporarily accommodated in the gas receiving portion passes through the plurality of dispersion holes provided in the gas receiving portion. Disperses horizontally outside the receiving part. And the gas disperse | distributed by the several dispersion hole is guide | induced to the several ventilation hole provided in the horizontal direction outer side rather than the gas receiving part. Therefore, in this configuration, it is possible to suppress the gas from flowing in the inner vent hole in a biased manner as compared with the case where the gas receiving portion is not provided.

  In the membrane module, a hollow portion is formed on the inner side in the horizontal direction of the membrane member so as to extend in the vertical direction, and the gas receiving portion is provided directly below the hollow portion via the main body portion. It is preferable.

  In this configuration, the gas receiving part is provided directly below the hollow part via the main body part, and the gas accommodated in the gas receiving part is dispersed horizontally outside the gas receiving part from the plurality of dispersion holes. Let That is, while providing a gas receiving portion at a position corresponding to a hollow portion where gas is less necessary to be supplied (directly below the hollow portion), gas is mainly supplied to the membrane member located on the outer side in the horizontal direction than the hollow portion. Therefore, the gas accommodated in the gas receiving part is dispersed from the plurality of dispersion holes to the outer side in the horizontal direction than the gas receiving part. Thereby, gas can be efficiently supplied to the area | region where the necessity of supplying gas is high, ie, the film | membrane member located in the horizontal direction outer side from a hollow part.

  The membrane module may be a one-end fixed type in which the upper end portion of the membrane member is fixed to the housing while the lower end portion of the membrane member is free. In the one-end fixed type membrane module, the support member is arranged in the hollow portion, and the upper end portion of the membrane member is fixed to the upper portion of the support member, while the lower portion of the support member is fixed to the housing. It can be illustrated.

  The membrane module may be a both-ends fixed type in which both the upper end portion and the lower end portion of the membrane member are fixed to the housing.

  ADVANTAGE OF THE INVENTION According to this invention, in the membrane module used for the liquid process etc. which remove the impurity in a liquid, the floating pollutant adhering to the outer peripheral part of a membrane member can be removed efficiently.

It is the schematic which shows an example of the water treatment apparatus provided with the membrane module which concerns on embodiment of this invention. (A) is sectional drawing which shows the membrane module which concerns on embodiment, (B) is the II-II sectional view taken on the line in (A). (A) is a top view which shows the diffuser of the membrane module which concerns on embodiment, (B) is the III-III sectional view taken on the line in (A). (A) is the schematic which shows the lower part of the membrane module which concerns on embodiment, and has shown the size and positional relationship of a housing, an air diffusion member, and a membrane member. (B) has shown the positional relationship of the housing and air diffusion member in a comparative example. (A) is the VA-VA sectional view taken on the line in FIG. 2, (B) is the VB-VB sectional view taken on the line in (A). (A), (B) is a graph which shows the performance evaluation result of a membrane module. It is the schematic which shows the modification of the aeration member in the membrane module which concerns on embodiment. It is the schematic which shows the modification of the membrane module which concerns on embodiment, and has shown the membrane module of a both-ends fixed type.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. The membrane module 1 which concerns on embodiment of this invention can be used for the water treatment apparatus 100 as shown, for example in FIG. The water treatment apparatus 100 is an apparatus for reducing the concentration of impurities contained in water by separating solid components contained in raw water (treatment target water) in the membrane module 1. Examples of impurities to be removed (substances to be removed) include turbidity in water such as river surface water, underground water, and lake water, and metal ions such as iron ions and manganese ions. It is not limited to metal ions.

[Overall structure of water treatment equipment]
The water treatment apparatus 100 includes a membrane module 1, a raw water tank 101, a gas supply apparatus 102, a treated water tank 103, a plurality of pipes 110 to 115 that connect them, a pump 120 provided in the pipe 110, and a pipe And a plurality of valves 130 to 135 provided in.

  The membrane module 1 can separate the solid content (floating pollutant) from the raw water to obtain membrane treated water with a reduced solid content concentration. As the membrane module 1, for example, a hollow fiber membrane module 1 having a hollow fiber membrane can be used. Examples of the hollow fiber membrane module 1 include a structure in which a hollow fiber membrane 3 as a membrane member 3 is provided in an elongated cylindrical housing 2, but is not limited thereto. The membrane module 1 only needs to have a function of separating solid content and membrane treated water from raw water, and may have a structure in which a separation membrane other than the hollow fiber membrane is provided in the housing 2.

  As a material for the hollow fiber membrane, various materials can be used, and are not particularly limited. For example, polyethylene, polypropylene, polyacrylonitrile, ethylene-tetrafluoroethylene copolymer, polychlorotrifluoroethylene, Polytetrafluoroethylene, polyvinyl fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, chlorotrifluoroethylene-ethylene copolymer, polyvinylidene fluoride, polysulfone, cellulose acetate In addition, it preferably contains at least one selected from the group consisting of polyvinyl alcohol and polyethersulfone, and polyvinylidene fluoride (PVDF) is more preferable from the viewpoint of film strength and chemical resistance. Arbitrariness.

  In the hollow fiber membrane module 1, the hollow fiber membrane is modularized and used for filtration. Specifically, as the hollow fiber membrane module 1, for example, a form in which dozens to hundreds of thousands of hollow fiber membranes are bundled and arranged in a U shape within the housing 2, and one end of the hollow fiber bundle is used. Forms that are collectively sealed with an appropriate sealing material, one end of each hollow fiber fiber bundle is sealed with an appropriate sealing material one by one (free state), and both ends of the hollow fiber fiber bundle are opened. The form etc. are mentioned. The shape of the hollow fiber membrane module 1 is not particularly limited, and may be, for example, a cylindrical shape or a screen shape. In particular, the one-end fixed type (one-end free type) hollow fiber membrane module 1 sealed in a free state is preferable in that it can efficiently peel and discharge the membrane adhering substance by gas back pressure cleaning.

  Examples of the filtration method in the hollow fiber membrane module 1 include external pressure total amount filtration, external pressure circulation filtration, and the like, and can be appropriately selected according to membrane separation treatment conditions and required performance. In terms of membrane life, a circulation method (external pressure circulation filtration method) that can simultaneously clean the surface of the filtration membrane is preferable, and in terms of equipment simplicity, installation cost, and operation cost, a full amount filtration method (external pressure full amount filtration method) is preferred. preferable.

  Further, in the external pressure filtration membrane module 1 such as external pressure total amount filtration and external pressure circulation filtration, the floating pollutant contained in the raw water has a high rate of being removed outside the membrane member 3 where the filtration is efficiently performed. Accordingly, the amount of floating contaminants adhering to the outer peripheral portion 31 of the membrane member 3 is larger than the amount of adhesion inside the membrane member 3. Therefore, the diffuser board 4 in this embodiment is particularly suitable for the membrane module 1 of the external pressure filtration method.

  The raw water tank 101 is a container for storing raw water containing floating contaminants. When the substance to be removed is, for example, metal ions, in the raw water tank 101 or an unillustrated water tank upstream of the raw water tank 101, the metal ions in the raw water are added with an additive such as an oxidant to obtain a solid content To be precipitated. When the substance to be removed is originally a solid content, the precipitation process can be omitted. As the gas supply device 102, for example, an air compressor can be used.

[Membrane module structure]
Next, the structure of the membrane module 1 according to the present embodiment will be described in detail. As shown in FIGS. 2A and 2B, the membrane module 1 includes a housing 2, a membrane member 3, an air diffuser 4 as an air diffuser, a support member 6, and a fixing member 7 (FIG. 5). Reference). The membrane module 1 of the present embodiment is a one-end fixed type (one-end free type) membrane in which the upper end of the membrane member 3 is fixed to the housing 2 while the lower end of the membrane member 3 is free. It is a module.

  As shown in FIG. 2A, the housing 2 has a cylindrical shape elongated in the vertical direction. The housing 2 includes a cylindrical portion 21 extending in the vertical direction, a lower lid portion 22 that closes a lower opening of the cylindrical portion 21, and an upper lid portion 23 that closes an upper opening of the cylindrical portion 21. The housing 2 is provided with a first port 11 (raw water inlet 11), a second port 12 (filtrated water outlet 12), a gas vent 13 and a gas supply port 14.

  The first port 11 is provided below the membrane member 3. In the present embodiment, the first port 11 is provided in the lower lid portion 22, but is not limited thereto, and may be provided in the cylindrical portion 21. The first port 11 functions as a raw water inlet for supplying raw water into the housing 2 in the filtration process, and also functions as a discharge port for discharging drain water generated in the backwashing process, the bubbling process, and the like from the housing 2.

  The second port 12 is provided above the membrane member 3. In the present embodiment, the second port 12 is provided in the upper lid portion 23, but may be provided in the cylindrical portion 21. The second port 12 functions as a filtered water outlet that discharges membrane treated water (membrane filtered water) from which suspended contaminants have been removed in the filtration process, and supplies fluid into the housing 2 in the backwash process. It also functions as a supply port.

  The gas vent 13 is provided above the first port 11 and below the second port 12. In the present embodiment, the gas vent 13 is provided in the cylindrical portion 21. The gas vent 13 functions as a discharge port for discharging the air in the housing 2 to the outside of the housing 2 as necessary in each process.

  The gas supply port 14 is provided below the membrane member 3. In the present embodiment, the gas supply port 14 is provided in the lower lid portion 22, but is not limited thereto, and may be provided in the cylindrical portion 21. The gas supply port 14 functions as a supply port for supplying air into the housing 2 in a state where water is filled in the housing 2 in the bubbling process. As shown in FIG. 2A, the air supplied from the gas supply port 14 flows into a guide tube 15 (guide unit 15) provided directly below a gas receiving unit 41 described later. Therefore, the air supplied from the gas supply port 14 is efficiently accommodated in the gas receiver 41.

  The membrane member 3 has an elongated shape extending in the vertical direction from the vicinity of the upper end of the cylindrical portion 21 to the vicinity of the lower end in the housing 2. As shown in FIG. 2B, the membrane member 3 has an annular shape in plan view so that the hollow portion 5 is formed inside. The membrane member 3 may constitute an annular membrane member 3 by arranging a plurality of hollow fiber fiber bundles in the circumferential direction, or may be constituted by a single hollow fiber fiber bundle formed in an annular shape. Good. In addition, the hollow part 5 can also be abbreviate | omitted and the film | membrane member 3 has a columnar shape in this case.

  As shown in FIG. 2A, the membrane member 3 is fixed to the housing 2 by a support member 6. In the present embodiment, the support member 6 includes a support column 6A and a lower connecting member 6B. However, the support member 6 may be any member that can fix the membrane member 3 to the housing 2 and is not limited to the form shown in FIG.

  The column 6A is disposed in the hollow portion 5 and extends in the vertical direction. The upper end of the membrane member 3 is fixed to the upper end of the support 6A. A lower connecting member 6B for fixing the support 6A to the lower end of the housing 2 is connected to the lower end of the support 6A.

  The air diffuser 4 serves to distribute and supply air supplied from the gas supply port 14 into the housing 2 in the region where the membrane member 3 is disposed in the bubbling process. The air diffuser 4 is provided below the membrane member 3 in the housing 2. As shown in FIGS. 3A and 3B, the air diffuser 4 includes a main body 40, a gas receiver 41, and a peripheral wall 42, which are integrally formed.

  The main body 40 has a disk shape (circular plate shape in plan view). A plurality of vent holes 43 are provided in the main body 40. The plurality of vent holes 43 are provided to supply air supplied from the gas supply port 14 below the diffuser panel 4 into the housing 2 to the membrane member 3 above the diffuser panel 4. This is a through-hole penetrating the diffuser board 4 in the vertical direction.

  In order to disperse air over a wide range of the membrane member 3, the plurality of vent holes 43 are arranged at intervals in the radial direction and the circumferential direction in the main body portion 40 of the diffuser panel 4. In the present embodiment, the plurality of vent holes 43 are provided in the main body portion 40 and are not provided in the peripheral wall portion 42. However, the diffuser board 4 may have one or a plurality of auxiliary ventilation holes 45 that are provided in the peripheral wall portion 42 in an auxiliary manner, as in a modification shown in FIG. Details of the plurality of vent holes 43 will be described later.

  The gas receiving portion 41 is provided below the main body portion 40 in order to temporarily store the gas supplied into the housing 2 through the gas supply port 14. Moreover, the gas receiving part 41 is provided just above the guide pipe 15 (guide part 15) mentioned above. In this embodiment, the gas receiving part 41 has a cylindrical shape. The outer diameter of the gas receiving portion 41 is smaller than the diameter of the main body portion 40. The upper end of the gas receiving portion 41 is connected to the lower surface of the main body portion 40. Thereby, an accommodation space 41 </ b> S surrounded by the inner peripheral surface of the gas receiving portion 41 and the lower surface of the main body portion 40 is formed. In addition, the shape of the main-body part 40 is not restricted to a cylindrical shape, For example, the cross-sectional shape may be a polygonal cylindrical shape.

  The gas receiver 41 has a plurality of dispersion holes 44. Each of the plurality of dispersion holes 44 is a through-hole penetrating a cylindrical wall constituting the gas receiving portion 41. The plurality of dispersion holes 44 are holes for dispersing the gas accommodated in the accommodation space 41 </ b> S of the gas receiving portion 41 to the radially outer side (horizontal direction outer side) below the gas receiving portion 41 below the main body portion 40. . In the present embodiment, the plurality of dispersion holes 44 are arranged at equal intervals in the circumferential direction. However, the present invention is not limited to this, and the intervals between adjacent ones may not be constant.

  The peripheral wall portion 42 is for suppressing the air supplied to the radially outer side from the gas receiving portion 41 through the plurality of dispersion holes 44 from moving to the radially outer side than the main body portion 40. The peripheral wall portion 42 has a cylindrical shape extending downward from the peripheral edge of the main body portion 40. The vertical dimension of the peripheral wall part 42 is smaller than the vertical dimension of the gas receiving part 41. That is, the lower end of the peripheral wall portion 42 is higher than the lower end of the gas receiving portion 41.

  The plurality of dispersion holes 44 provided in the gas receiving portion 41 are provided at a position higher than the lower end of the peripheral wall portion 42 (position close to the main body portion 40). Thereby, the effect which suppresses that the air supplied to the radial direction outer side rather than the gas receiving part 41 through the some dispersion hole 44 moves to a radial direction outer side from the main-body part 40 can be heightened.

  As shown in FIG. 3, in the present embodiment, all the air holes 43 are provided in the main body portion 40 on the radially outer side (horizontal direction outer side) than the gas receiving portion 41. The vent hole 43 may be provided on the inner side in the radial direction from the gas receiving portion 41 in the main body portion 40.

  As shown in FIG. 3A, the plurality of vent holes 43 are arranged on a plurality of circumferences C <b> 1 to C <b> 4 centering on the center A of the main body 40 of the diffuser panel 4. The plurality of vent holes 43 include a first vent hole 431 arranged on the outermost circumference C1, a second vent hole 432 arranged on a circumference C2 having a diameter smaller than the circumference C1, and a circumference. It has the 3rd ventilation hole 433 arranged on the circumference C3 smaller in diameter than C2, and the 4th ventilation hole 434 arranged on the circumference C4 smaller in diameter than the circumference C3. The vent holes 43 on each circumference are arranged at equal intervals, but the present invention is not limited to this. In the present embodiment, the vent holes 43 are arranged on the four circumferences C1 to C4, but the number of circles may be plural other than four. Moreover, some vent holes 43 may be provided at positions other than on the circumference.

  As shown in FIG. 3A, in the present embodiment, the plurality of ventilation holes 43 arranged on the plurality of circumferences C1 to C4 are the plurality of ventilation holes 431 arranged on the outermost circumference C1. Is narrower than the interval between the plurality of vent holes 432, 433, and 434 arranged on the circumferences C2 to C4 on the radially inner side. That is, the arrangement density of the plurality of vent holes 431 arranged on the outermost circumference C1 is such that the plurality of vent holes 432, 433, and 434 arranged on the radially inner circumferences C2 to C4 are arranged. Higher than placement density. In the present embodiment, the intervals between the plurality of vent holes 434 arranged on the innermost circumference C4 are the same as the plurality of vent holes 431 arranged on the circumferences C1 to C3 on the radially outer side. It is wider than the interval between 432 and 433. Moreover, in this embodiment, the space | interval of the vent holes 43 is narrower toward the radially outer side. However, the interval between the vent holes 43 may be constant regardless of the radial position.

  The inner diameter of the first vent hole 431 provided on the outermost circumference C1 is larger than the inner diameters of the vent holes 432, 433, and 434 provided on the radially inner side. Therefore, as compared with the case where the inner diameters of the plurality of vent holes 43 are the same (Example 2 described later), the ratio of the gas guided to the upper side of the diffuser 4 through the first vent holes 431 located on the outermost side in the radial direction. Can be increased. Thereby, the floating pollutant SS adhering to the outer peripheral portion 31 of the membrane member 3 can be removed more efficiently than in the second embodiment (see the graph in FIG. 6A described later).

  In the present embodiment, the inner diameters of the vent holes 432, 433, and 434 are the same, but are not limited thereto. For example, the first vent hole 431, the second vent hole 432, the third vent hole 433, and the fourth vent hole 434 may be configured so that the inner diameter gradually decreases.

  FIG. 4 (A) is a schematic view showing the lower part of the membrane module 1 according to the embodiment, and shows the size and positional relationship of the housing 2, the diffuser board 4 and the membrane member 3, and FIG. The positional relationship between the housing 2 and the diffuser board 204 in the comparative example is shown.

  As shown in FIG. 4A, the diameter D1 of the diffuser 4 (the horizontal dimension D1 in the diffuser 4) is larger than the dimension D2 from one side of the membrane member 3 in the horizontal direction to the other side. Is also big. In the present embodiment, the first vent hole 431 provided on the outermost circumference C1 is positioned such that the center A1 of the first vent hole 431 is radially outward (horizontal outer side) from the membrane member 3. It is provided as follows.

  Thus, since the 1st ventilation hole 431 is provided so that it may be located in the radial direction outer side rather than the membrane member 3, in the bubbling process after a backwash process, some gas supplied in the membrane module 1 Is guided to the upper side of the air diffuser 4 by the first vent hole 431 located on the outer side in the radial direction from the membrane member 3, and floats adhering to the outer peripheral portion 31 of the membrane member 3 by rising in the liquid as it is. The pollutant SS can be reached.

  5A is a cross-sectional view taken along line VA-VA in FIG. 2, and FIG. 5B is a cross-sectional view taken along line VB-VB in FIG. As shown in FIGS. 4A, 5A, and 5B, the inner diameter D3 of the housing 2 (the inner dimension D3 in the horizontal direction in the housing 2) is larger than the diameter D1 of the diffuser panel 4. Therefore, a gap G is formed between the inner surface of the housing 2 and the diffuser board 4. The gap G can function as a passage for guiding the suspended pollutant SS that has been peeled off from the surface of the membrane member 3 by performing the bubbling process below the diffuser 4. Thereby, the floating pollutant SS removed from the surface of the membrane member 3 is efficiently discharged out of the housing 2 through the first port 11 (see FIG. 2).

  On the other hand, in the diffuser board 204 in the comparative example shown in FIG. 4B, the diameter D11 of the diffuser board 204 is smaller than the dimension D2 from one side of the membrane member 3 in the horizontal direction to the other side. Further, in the diffuser board 204 in the comparative example, the vent hole 432 provided on the outermost circle is provided such that the center A11 of the vent hole 432 is located on the radially inner side of the membrane member 3. .

  In the present embodiment, as shown in FIGS. 5A and 5B, the air diffuser 4 is fixed to the housing 2 by a plurality of fixing members 7. In the present embodiment, each fixing member 7 is a substantially L-shaped member, but is not limited thereto. In order to fix the diffuser 4 in the housing 2 by the fixing member 7, first, one end of each fixing member 7 is fixed to the diffuser 4 using a fixing means such as welding. Thereafter, the air diffuser 4 to which the plurality of fixing members 7 are fixed is fitted into a predetermined position in the housing 2 and fixed to the inner surface of the housing 2 at that position by a fixing means such as welding. Thereby, the diffuser board 4 can be fixed with respect to the housing 2 in the state arrange | positioned in the center part in the housing 2. FIG.

[Operation of water treatment equipment]
In the water treatment apparatus 100, a plurality of processes including a filtration process, a backwash process, and a bubbling process are performed.

  First, before a filtration process is performed, raw water is filled in the housing 2 as a preparation process (first water filling process). When the raw water is filled in the housing 2 in the first water filling step, the valve 132 is opened, so that the fluid containing air in the housing 2 is piped from the gas vent 13 provided in the housing 2. It flows out to 112.

  In the filtration step, the pump 120 is operated with the valves 130 and 131 open. Thereby, the raw water in the raw water tank 101 is supplied into the membrane module 1 from the first port 11 (raw water inlet 11) through the pipe 110. The removal target substance contained in the supplied raw water is captured by the membrane member 3. Membrane treated water (filtered water) that has passed through the membrane member 3 and has a reduced concentration of the substance to be removed flows out from the second port 12 (filtrated water outlet 12) to the pipe 111 and is collected in the treated water tank 103.

  When the filtration process is performed in the membrane module 1, solid content (floating contaminants) including the substance to be removed adheres to the membrane member 3. When a predetermined time elapses after the filtration step is started in the membrane module 1, the filtration step is temporarily stopped and back washing (back pressure washing) for removing the solid content adhering to the membrane member 3 from the membrane member 3 is performed. A process and a bubbling process are performed.

  In the backwashing process, in order to float the solid content deposited and stuck on the surface of the membrane member 3 from the membrane member 3, a flow of fluid in the opposite direction to the filtration step is formed in the membrane module 1. That is, the valves 134 and 135 are opened, and air is supplied from the gas supply device 102 such as an air compressor through the second port 12 (filtered water outlet 12). The air that has flowed into the housing 2 acts on the solid content adhering to the surface of the membrane member 3. Thereby, it will be in the state where solid content floated partially from the surface of the membrane member 3. FIG.

  When the fluid passes through the membrane member 3 in the housing 2, the fluid is discharged out of the housing 2 through the first port 11 (raw water inlet 11). The drain water discharged out of the housing 2 is drained through the pipe 114.

  The solid content that is partially lifted from the surface of the membrane member 3 by the backwashing step is peeled off from the surface of the membrane member 3 in the subsequent bubbling step. In addition, as the fluid in the backwashing step, a liquid such as water may be used instead of the air supplied from the gas supply device 102 as described above.

  Before the bubbling process is performed, raw water is filled in the housing 2 as a preparation process (second water charging process). When the raw water is filled into the housing 2 in the second water filling step, the valve 132 is opened, so that the fluid containing the air in the housing 2 is piped from the gas vent 13 provided in the housing 2. It flows out to 112.

  In the bubbling process, while the valves 134 and 135 are closed, the valve 133 is opened and the gas supply device 102 is operated, whereby compressed air is sent through the pipe 113 and is supplied from the gas supply port 14. It is supplied into the housing 2. In this bubbling step, the membrane member 3 is shaken by the air bubbles supplied into the membrane module 1, whereby the solid content on the surface of the membrane member 3 is peeled off.

  When the bubbling process is completed, the water in the housing 2 is drained through the pipe 114 (drainage process). After the drainage process, the filtration process is started again.

[Evaluation results]
6A and 6B are graphs showing the performance evaluation results of the membrane module. 6 (A) and 6 (B), the first embodiment is a film in which the diffuser 4 shown in FIGS. 3 (A) and 3 (B) is disposed in the housing 2 in the arrangement as shown in FIG. 4 (A). Module 1. In the air diffuser 4 in Example 1, the inner diameter of the vent hole 431 located on the outermost periphery was 4 mm, and the inner diameters of the vent holes 432, 433, and 434 located on the radially inner side were 3.5 mm.

  Example 2 is a membrane module 1 having the same structure as Example 1 except that the outermost peripheral vent hole 431 is smaller than Example 1. In the air diffuser 4 in Example 2, the inner diameters of all the vent holes 431, 432, 433, and 434 were set to 3.5 mm.

  The comparative example is a membrane module in which a diffuser board 204 shown in FIG. The diffuser board 204 in this comparative example omits the outermost vent holes 431 of the diffuser board 4 in the first embodiment, and has only vent holes 432, 433, and 434 on the inner side. In the comparative example, the inner diameters of all the vent holes 432, 433, and 434 were set to 3.5 mm.

  6 (A) and 6 (B) show a cycle in which water treatment (filtration process) is performed for a predetermined time in each of Example 1, Example 2 and Comparative Example, and then a backwash process and a bubbling process are performed. When it continues, the adhesion amount of the floating pollutant SS with respect to the film | membrane member 3 is compared. One cycle used for the evaluation consists of a first filling process, a filtration process, a backwashing preparation process, a backwashing process, a pressure relief process, a second filling process, a bubbling process, and a draining process. Become.

  Specifically, the first water filling step is a water filling step for preparing the filtration step, and is a step of filling the housing 2 with raw water. The filtration step is a step of filtering the raw water supplied from the raw water inlet 11 into the housing 2 in the membrane module 1 and discharging it from the filtered water outlet 12. The backwashing preparation process is a process for preparing the backwashing process. The backwash process is a process of supplying air from the filtrate outlet 12 using the gas supply device 102. The depressurization step is a step of reducing the pressure in the filtrate outlet 12 that is at a high pressure by performing a backwashing step. The second water filling step is a water filling step for preparing the bubbling step, and is a step of filling the housing 2 with raw water. The bubbling step is a step of supplying air from the gas supply port 14 using the gas supply device 102 into the housing 2 filled with raw water. The draining process is a process of draining water in the housing 2 after the bubbling process is performed.

  In this evaluation, the time of each process in one cycle is 29 seconds for the first water filling process, 600 seconds for the filtration process, 2 seconds for the backwash preparation process, 10 seconds for the backwash process, Was 10 seconds, the second water filling step was 5 seconds, the bubbling step was 60 seconds, and the draining step was 20 seconds. These conditions are used for the accelerated test and are different from the conditions used in the actual line.

  As shown in FIGS. 6A and 6B, in the comparative example, the adhesion amount of the floating pollutant SS to the membrane member 3 continues to increase with the elapsed time from the start of evaluation to the end of evaluation (after about 7 days). . Accordingly, the differential pressure in the membrane module 1 (the difference between the pressure on the raw water inlet 11 side and the pressure on the filtered water outlet 12 side) is also increasing.

  On the other hand, in Example 1 and Example 2, compared with the comparative example, the adhesion amount of the floating pollutant SS to the membrane member 3 at the end of the evaluation is reduced to about ¼ of the comparative example. In Example 1 and Example 2, in the initial stage of evaluation, the amount of floating pollutant SS adhering to the membrane member 3 tends to increase, but the increase in the amount of adhesion is suppressed after the middle of the evaluation. In the first embodiment, the amount of the floating pollutant SS attached to the membrane member 3 is further reduced as compared with the second embodiment. Moreover, in Example 1 and Example 2, the increase in the differential pressure is also suppressed as compared with the comparative example.

[Summary of Embodiment]
In the present embodiment, in the diffuser panel 4 as the diffuser member, a part of the plurality of vent holes 43 is provided so as to be positioned on the outer side in the horizontal direction with respect to the membrane member 3. In the subsequent bubbling process, a part of the gas supplied into the membrane module 1 is guided to the upper side of the diffuser 4 by the vent holes 43 positioned on the outer side in the horizontal direction from the membrane member 3, and ascends in the liquid as it is. By doing so, it is possible to reach the suspended contaminant SS attached to the outer peripheral portion 31 of the membrane member 3. Thus, in this embodiment, since a part of gas supplied in the membrane module 1 can be reliably supplied to the outer peripheral part 31 of the membrane member 3, it adheres to the outer peripheral part 31 of the membrane member 3. The floating contaminant SS can be efficiently peeled off from the surface of the membrane member 3 and removed.

  In the present embodiment, the horizontal inner dimension of the housing 2 is larger than the horizontal dimension of the diffuser panel 4. Thus, since the inner dimension of the housing 2 is larger than the dimension of the diffuser board 4, a gap is formed between the inner surface of the housing 2 and the diffuser board 4. This gap can function as a passage for guiding the suspended pollutant SS that has been peeled off from the surface of the membrane due to the bubbling process to a position below the diffuser 4. Thereby, the floating pollutant SS removed from the surface of the membrane can be efficiently discharged out of the housing 2.

  In the present embodiment, of the plurality of vent holes 43, the inner diameter of the vent hole 43 provided on the outermost side in the horizontal direction is larger than the inner diameter of the vent hole 43 provided on the inner side in the horizontal direction. Therefore, in this embodiment, compared with the case where the internal diameter of the some vent hole 43 is the same, the ratio of the gas guide | induced to the upper direction of the diffuser board 4 through the vent hole 43 located in the outermost horizontal direction can be raised. it can. Thereby, the floating pollutant SS adhering to the outer peripheral portion 31 of the membrane member 3 can be more efficiently removed.

  In the present embodiment, the air diffuser 4 includes a disc-shaped main body 40, a gas receiving portion 41 that is provided below the main body 40, and temporarily stores the gas supplied into the housing 2. The plurality of vent holes 43 are provided in the main body portion 40 on the outer side in the horizontal direction with respect to the gas receiving portion 41, and the gas receiving portion 41 allows the gas contained in the gas receiving portion 41 to flow from the main body portion 40. A plurality of dispersion holes 44 for dispersing the gas receiving portion 41 outward in the horizontal direction below the gas receiving portion 41 are provided. Therefore, the gas temporarily accommodated in the gas receiving portion 41 is dispersed more outward in the horizontal direction than the gas receiving portion 41 through the plurality of dispersion holes 44 provided in the gas receiving portion 41. On the other hand, the main body portion 40 is provided with a plurality of vent holes 43 on the outer side in the horizontal direction than the gas receiving portion 41. Therefore, in this embodiment, the ratio by which the gas is guided above the diffuser board 4 on the outer side in the horizontal direction can be increased. In addition, in this configuration, the gas is dispersed by the plurality of dispersion holes 44 provided in the gas receiving portion 41, so that compared to the case where the gas receiving portion 41 is not provided, a part of the plurality of ventilation holes 43 is provided. It is possible to prevent the gas from being biased.

  In the present embodiment, the hollow portion 5 is formed on the inner side in the horizontal direction of the membrane member 3 so as to extend in the vertical direction, and the gas receiving portion 41 is located below the main body portion 40 at a position corresponding to the hollow portion 5. Is provided. In this embodiment, while providing the gas receiving part 41 in the position corresponding to the hollow part 5 with low necessity to supply gas, on the other hand, the gas is focused on the membrane member 3 located on the outer side in the horizontal direction than the hollow part 5. In order to supply, the gas accommodated in the gas receiving portion 41 is dispersed from the plurality of dispersion holes 44 to the outside in the horizontal direction from the gas receiving portion 41. Thereby, gas can be efficiently supplied to the area | region where the necessity of supplying gas is high, ie, the horizontal direction outer side than the gas receiving part 41. FIG. In the hollow portion 5 formed inside the membrane member 3, for example, a support member 6 that supports the membrane member 3 in the housing 2 can be disposed.

[Modification]
As mentioned above, although embodiment of this invention was described, this invention is not limited to these embodiment, A various change, improvement, etc. are possible in the range which does not deviate from the meaning.

  FIG. 7 is a schematic diagram illustrating a modification of the diffuser 4 in the membrane module 1 according to the embodiment. The air diffuser 4 of this modification has a plurality of auxiliary ventilation holes 45 provided in the peripheral wall portion 42 in an auxiliary manner. The plurality of auxiliary vent holes 45 are arranged at intervals in the circumferential direction on the peripheral wall portion 42. In this modification, in the bubbling process after the backwash process, a part of the gas supplied into the membrane module 1 is located above the diffuser panel 4 by the auxiliary vent holes 45 located on the outer side in the horizontal direction than the membrane member 3. The floating pollutant SS attached to the outer peripheral portion 31 of the membrane member 3 can be reached by ascending as it is in the liquid.

  In the above embodiment, as the membrane module 1, a single-end fixed type (one-end free type) membrane module has been exemplified. However, the membrane module 1 has both ends of the membrane member 3 fixed in the housing 2 as shown in FIG. Both end fixed type membrane modules may be used. As shown in FIG. 8, the both-ends fixed type membrane module 1 includes a housing 2, a membrane member 3, and a diffuser panel 4 as a diffuser member, and a diameter (horizontal dimension) in the diffuser panel 4. Is larger than the dimension from one side of the membrane member 3 in the horizontal direction to the other side, and a part of the plurality of vent holes 43 (outermost vent hole 431) is more horizontal than the membrane member 3 It is provided so that it may be located outside. The features such as the size and positional relationship of the membrane member 3, the diffuser 4 and the housing 2 in the both-ends fixed membrane module 1 shown in FIG. 8 are the same as those in the embodiment shown in FIGS. Therefore, detailed description is omitted.

  In the said embodiment, although the case where the membrane module 1 was used for water treatment was illustrated, it is not restricted to this, The membrane module 1 can also be used for the liquid processing which removes impurities in liquids other than water.

  In the said embodiment, although the housing 2 had the cylindrical shape, it is not restricted to this, Another shape may be sufficient.

  In the said embodiment, although the air diffusing member 4 was provided with the disk-shaped main-body part 40, the gas receiving part 41, and the surrounding wall part 42, it is not restricted to this. In the air diffusing member 4, one or both of the gas receiving portion 41 and the peripheral wall portion 42 can be omitted. Moreover, the main-body part 40 of the air diffusing member 4 is not limited to a disk shape, but may be another shape such as a block shape.

  In the embodiment, the air diffusing member 4 is fixed to the housing 2 via the support member 6, but may be directly fixed to the housing 2 without using the support member 6. Further, the air diffusing member 4 may be fixed to the membrane member 3 instead of being fixed to the housing 2.

  In the said embodiment, although the gas supplied in the housing 2 in a bubbling process was air, gases other than air may be used for a bubbling process.

1 Membrane Module 2 Housing 3 Membrane Member 4 Air Diffuser (Air Diffuser)
DESCRIPTION OF SYMBOLS 5 Hollow part 6 Support member 7 Fixing member 11 1st port 12 2nd port 13 Gas vent 14 Gas supply port 31 The outer peripheral part of a membrane member 40 Main body part 41 Gas receiving part 42 Perimeter wall part 43 Vent hole 44 Dispersion hole 100 Water treatment apparatus

Claims (7)

A housing;
A membrane member provided in the housing;
An air diffusion member provided below the membrane member in the housing and having a plurality of vent holes for supplying gas to the membrane member;
The dimension of the diffuser member in the horizontal direction is larger than the dimension of the membrane member in the horizontal direction,
A membrane module, wherein a part of the plurality of vent holes is provided so as to be located outside the membrane member in the horizontal direction.   The membrane module according to claim 1, wherein a gap is formed between the housing and the air diffusing member.   The membrane module according to claim 1 or 2, wherein an inner diameter of the outermost vent hole among the plurality of vent holes is larger than an inner diameter of the vent hole provided on the inner side. The air diffuser is
A plate-like main body provided with the plurality of vent holes;
A gas receiving portion provided below the main body portion for temporarily storing the gas supplied into the housing;
The plurality of vent holes are provided outside the gas receiving portion in the horizontal direction in the main body portion,
The said gas receiving part has a some dispersion hole for disperse | distributing the gas accommodated in the said gas receiving part to the outer side of the horizontal direction rather than the said gas receiving part under the said main-body part. The membrane module according to any one of the above. On the inner side in the horizontal direction of the membrane member, a hollow portion is formed so as to extend in the vertical direction,
The membrane module according to claim 4, wherein the gas receiving part is provided directly below the hollow part via the main body part.   The upper end portion of the membrane member is fixed to the housing, while the lower end portion of the membrane member is a one-end fixed type in a free state. Membrane module. The membrane module according to any one of claims 1 to 5, wherein the membrane member is a both-ends fixed type in which both an upper end portion and a lower end portion of the membrane member are fixed to the housing.